听觉注意强化惊反射前脉冲抑制的神经机制

惊反射的前脉冲抑制 (PPI) 是一种人和动物所共有的感觉运动门控过程。注意对PPI的调节已成为重要的研究课题。近期的研究表明，依赖于杏仁核，对一个前脉冲声音的恐惧条件化可强化大鼠对该声音的注意，并特异性地增强由该声音所引发的PPI。而更重要的是，依赖于后顶叶，已被恐惧条件化的前脉冲声音与掩蔽噪音之间的知觉分离通过促进大鼠对该声音的空间选择性注意而进一步增强PPI。杏仁核和后顶叶分别接受两处不同的次级听皮层区（TE3和TE2背区）的投射。本项目将探索，包含TE3-杏仁核通路与包含TE2背区-后顶叶通路如何参与声音特征选择性注意和空间选择性注意对大鼠PPI的调节。实验工作包括：1）建立能同时体现这两种注意对PPI调节的行为模型；2）考察恐惧条件化和知觉分离如何影响这两条通路中各脑区的对前脉冲声音的电生理反应；3）考察药物阻断这两条通路中的一些关键性神经活动在行为层次和电生理层次上的影响作用。

Prepulse inhibition of the startle reflex (PPI) has been widely considered as a model of the sensorimotor gating process in both humans and animals. The top-down attentional modulation of PPI has become an important research issue. Recent studies have shown that fear conditioning of a prepulse, which depends on the amygdala, facilitates rats' attention to the conditioned prepulse and specifically enhances PPI induced by this prepulse. Moreover, perceived spatial separation between the conditioned prepulse and a masker noise, which depends on the posterior parietal cortex (PPC), further enhances PPI by facilitating selective spatial attention to the conditioned prepulse. The amygdala and the PPC receive axonal projections from two separate secondary auditory cortical areas (TE3 and TE2/dorsal), respectively. Using rats as the laboratory animal subjects, this project will investigate how the neural pathway including the TE3 and amygdala and the neural pathway including the TE2/dorsal and PPC participate in the feature-specific and the spatially-selective attentional modulation of PPI. Specifically, this project will 1) establish a new behavioral model for studying attentional modulation of PPI with both feature and spatial specificities, 2) examine how fear conditioning and perceived spatial separation affect neural activities in the brain regions within the two pathways by electrophysiological recordings, and 3) examine the effects of locally pharmacological blocking of some important neural activities in the two pathways on the attentional enhancement of both PPI and electrophysiological responses to the prepulse stimulus.